Fluid pressure applying mechanism for fluid pressure actuated devices



PoRKER-r 2,955,427 Y MEcHANIsM FOR FLUID TED DEVICES Oct. l1, 1960 L. G,

FLUID PRESSURE APPL ING PRESSURE ACTUA Filed June 26,

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ATTORNEYS United States Patent() FLUID PRESSUREAPPLYING IVIECHANISM FOR FLUID PRESSURE ACTUATED DEVICES Lloyd G. Porkert, 4819 Barrymore Drive, Washington D.C., assigner of twenty percent to Thomas K. Hampton, Bolling Air Force Base, Washington, D.C.

Filed June 26, 1959, Ser. No. 823,232

Y 14 Claims. (Cl. (S0-54.6)

'Ihis invention relates tol devices for first taking up the slack and increasing the force ratio in iluid pres-sure actuated devices.

An object of the invention is to provide a common actuator which has force applied thereto that actuates a relatively large area piston to apply a low pressure force to a pressure system and which continues after the application of the low pressure to apply a-high pressure.

A further object of the invention is to provide a iiuid pressure applicator having a `common force applying medium which rst subjects a system to be activated -to a low pressure and following this the common actuator continues its motion to apply a high pressure to the system 'being activ-ated with the last application of high pressure being isolated from the low pressure applying system in that any possible leakage in the low pressure applying means does not affect application of high pressure.

Another object of the invention is to provide a uid pressure applicator having a common force applying medium which lirst subjects a system to be activated to low pressure with a closed low pressure system containing actuating fluid in at least a portion of the low presl sure system and following this application of low pressure the common actuator continues its motion to apply a high pressure to the system being activated with the last application ci high pressure being isolated from the 4low pressure applying system in that any possible leakage in the low pressure applying means `does not aect application of high pressure.

Another object of the invention is to provide in a hydraulic brake Iapplying .system an actuator which moves a low pressure piston in a cylinder through a pressure spring connection against a second biasing spring and against uid connected with the braking system to first take up slack in the brakes by seating the brake shoes against the drums ordiscs until movement of the pressure builds up to resist further movement of the low pressure piston following which the actuator moves a high pressure smaller sized piston to force iluid to apply the brakes whereby low pressure is built up rapidly to :take the slack out of the brakes lfollowing which high pressure is applied to set the brakes and upon release of the force applied, vent means permit lthe piston to return to retracted positionl under the biasing action against the actuator and pistons to restore the system to a re-v tracted condition.l

Yet a further object of the invention is to provide a hydraulic. force applying mechanism that applies force quickly at a low pressure followed by high pressure force yet which is relatively small in size and economical to fabricate and yet provides a maximum of reliability of operation by having the high pressure system in at least va portion of its pressure application isolated from the low pressure force applying medium.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiment thereof shown in the accompanying drawings and it comprises the lfeatures of construction, combination of elements and arrangement of parts that will be exemplied in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims. Y j

For a more complete understanding of the nature and scope of this invention reference can be had to the following detailed descrip-tion, taken together with the accompanying drawings, in which:

Fig. l isa generally vertically cross sectional side view of the mechanism;

Fig. 2 is an end view of the left-hand end of the apparatus of Fig. l;

Fig. 3 is a modified form of check valve for the apparatus on an enlarged scale; and

Fig. 4 is a sectional view along line 4 4 of Fig. 3.

A fluid pressure actuating mechanism is generally indicated at z10 and discharges uid under pressure to a conduit 11 that is connectable to a duid-actuated mechanism (not shown). The uid actuated mechanism may be lluid actuated brakes or other uid actuatable mechanism where a sequence of pressures is needed; i.e., a relatively low pressure in relatively large volume to irst move the actuated apparatus as taking up the slack in brakes followed by application of a higher pressure in a relatively lower volume to actuate the brakes or the like.

A mainybody 12 preferably of metal that may be a casting or otherwise formed has a generally cylindrical lower portion 13 and a top reservoir portion 14. The body '12 may be formed with a protruding boss 15 at one end and a bott-om slightly enlarged portion 16 in which is formed a passageway with an installed check valve as will be explained. The main body may equally as well l take other shapes.

.of relatively greater size that extends to the right in the main body to a right-hand end opening 18 that is internally threaded. Received in the internally threaded end 18 is a threaded end plug 19 hav-ing a central aperture 20 in line with the high pressurechannelway 17 and the low pressure channelway 18. The plug 19 is formed on i-ts left end with a recessed pocket and at the right-h-and end with a recessed threaded pocket 22 to receive a packing gland as will be described.

Received in the high pressure of first cylinderway 17 is a high pressure piston 23 that extends through the low pressure or second cylinderway 18 and on through the aperture 20 in end plug 19 to where the outer end, shown ybroken -away at 23a may be further connected to a power or force applying source such as a brake pedal or actuating lever. Received in the recessed pocket 22 in plug 19 is a suitable packing gland seal or nut 24 that may seat against lan O-ring seal 25. The left hand or pressure applying end of piston 23 is provided with sealing rings 23b so that a high pressure may be developed for the system to be supplied or actuated that is connected at '11. A suitable high pressure conduit iitting generally indicated at 25 is screwed into the end of the high pressure cylinderway 17 extending out through boss 15.

Mounted in the low pressure or second cylinderway 18 is a low pressure or second piston 26 that is apertured at yits center 26a to receive the piston 23 that extends therethrough. A suitable seal between surrounding piston 26 and piston rod extension 23h is provided in piston 26 at 26b. Low pressure piston 26 is formedV with protruding bosses on eachv end at 26e and 26d. A biasing coil spring 27 is positioned between the pressure applying face 26e at the left end of low pressure piston 26 and the forward end `18 of low pressure cylinderway 18 so that one end of the spring-27 seats around boss 26e on piston 26. Also in the outer periphery of piston26 is an annular recess 26]c that receives a sealing ring 26g such as an O-ring.

A resilient and biasing spring 28 is received over the right-hand portion of piston 23 at its extension as a rod portion 23b with one end of spring 28 received by boss 26d on piston 26 and the other end pressing against a cup-shaped ring Washer 28a held onpiston rod portion 23b by a split ring 28h that is received in an annular recess 28e in low pressure piston rod portion 23b. The low pressure or second piston 26 is thereby biasly mounted on piston rod portion 23b of the high pressure piston 23. In the normal position of piston rod 23b wherein little or no actuating force is applied at 23a, spring 27 tends to move piston 26 to the right against the oppositely positioned spring 28 to thereby restore or hold piston 26 and piston rod 23b and its piston 23 in a retracted position.

A first conduit or passageway generally indicated at 29 is formed in the body 12 to connect the forward end 18" of the second cylinderway 18 with the high pressure cylinderway 17 at a position spaced ahead of the pressure applying face 23C of piston 23 as it rests in its retracted position. This. passageway 29 comprises iirst a drilled or formed passage 29a leading to the forward end of the cylindrical body portion 13 where its end is closed by a suitable sealing screw and gasket indicated at 30. The second part of the passageway 29 is a formed cavity 29b extending generally transverse to the cylinder passageway 17 where it narrows in diameter at passage end 29C. The passageway 29b intersects the passage 29a so as to directly form a liquid or fluid passageway for uid such as hydraulic oil that will fill same and the cylinderways 17 and 18 ahead of the respective pistons 23 and 26 therein. Passageway portion 29b is internally threaded to receive first the check valve assemblies 31 and 32 which seat against each other and with the inner one 32 seating against the shoulder formed between the passages 29b and 29C. A cap closure screw 33 having a sealing gasket 33a is received in the threaded outer end of aperture 29h. that the lower forward portion 16 of the main body 12 of the actuating mechanism is milled o or otherwise formed with a suitable flat surface 16a so that a sealing iit is obtained between the washer 33a and that portion 16 of the body member.

The check valves 31 and 32 may be of a conventional spring pressed ball type having balls in seats so positioned that iiuid is prevented from iiowing back from first cylinderway 17 to second cylinderway 18.

A vent passageway or conduit 34 is formed in the body 12 and connects, as here illustrated, at one end with passageway portion 29a so as to be in communication with cylinderway 18 while the other end communicates with cylinder passageway 17 at a position intermediate the passage 29e connecting with cylinder passageway 17 and the pressure applying face or end 23e` of the high pressure or rst piston 23 as it rests in its retracted position as illustrated in Fig. l. In the structure illustrated, passageway 34 has a closure screw 34a to close off the exterior end of the drill hole. This vent 34 serves to function, first as a fluid passage to cylinderway 17 on the initial movement of cylinder 26 to force iiuid from 18 to 17 until the portion 23 closes off passage 34 connection to 17 and second, as a vent for normalizing the pressure from high pressure cylinderway 17 and its connection 11 to the low pressure piston channelway 18 and the reservoir 14 as piston 23 is retracted to the right on release of force applied at 23a.

Passageway or conduit 29 comprising the sections 29a and 29b thereof supplies uid from the low pressure It will be observed in Figures 1 and 2' cylinderway 18 to the high pressure cylinderway 17 until slack is taken up and the low pressure applied by movement of piston 26 to the left is interrupted by the buildup of back pressure in the system after the actuated mechanism is initially seated.

The reservoir 14 above-cylinderway 18 is formed as a cavity in the upper portion of body 12 and a suitable* top plate 35 and gasket 35ais held on by screws 36.v

Top 35` is provided with a suitable in-turned boss 35b thatis apertured and threaded to receive a removable iilling screw plug 37 having a sealing gasket 37a.

Reservoir 14 is connected with two vent passageways 38 and 39 positioned to communicate with cylinderway 18 to either side of piston 26 as it rests in its retracted position. A passageway 40 is also formed in the body 12 to provide a communication between reservoir 14 and cylinderway 18 at a position spaced between vent 39 adjacent and ahead of the pressure applying face 26e of piston 26 and the forward end.18" of cylinderway 18. Passageway 40 has an enlarged threaded bore 40a at its upper end in communication with reservoir 14 to receive a check valve assembly 41 which prevents fiow through passageway 40 from cylinderway 18 to the reservoir 14 but allows flow of replacement or make up iiuid from reservoir 14 toy cylinderway 18 for the system.

M oded check valve A modied form of check valve is generally indicated at 42 in Figures 3 and 4 that may be used as a substitute for the serially arranged ball check valves 31 and 32 illustrated for passageway portion 29b of passageway 29.

In the modified form of check valve 42 there is an exteriorly threaded plug-like member 43 received in recess 29h and formed with an internal cylindrical recess 44 extending downwardly to the closed bottom end 45.that has a central boss 46 with an aperture 46a extending vertically therethrough and through which fluid is forced from rst passage portion 29a. Seated in the bottom end of 42 about boss 46 is an annular gasket or washer seat 47 of rubber or suitable composition material which serve as a seat for the movable valve element 48 that is in the form of a piston received for reciprocable movement in recess 44. Valve element 48 is formed with radially extending spaced apart guide lands 48a which guide the element 43 in its up and down. valve movement in recess 44. Valve member 48 is formed with a recessed lower end 48b thereby forming a sharp annular lower end portion 48e that seats against the valve seat 47 about the upstanding boss 46. The upper end of valve element 48 has a recess 48d within which the lower end of a cornpression bearing spring 49 nests while the upper end of the spring 49 seats against the shoulder 29d at the upper end of passageway 29 adjacent the reduced apertured portion 29C where it joins cylinderway 17 of the high pressure or first piston 23.

Operation In operation, application of force on common actuator piston rod 23b at 23a causes the rod to move to the left and the resilient connection 28 between rod 23b and piston 26 urges the piston 26 to the left against compression spring 27 and the fluid in the system and particularly the cylinderway 18 closing off the vent passageway 39 in normal operation. Thus, a relatively low pressure is afforded for the system as connected at 11 and because of the relatively large volume of iiuid displaced by piston 26, movement is relatively quick to take up slack in the system as there is at rst relatively low resistance to be overcome. As soon as the slack is taken up, the pressure in the system ahead of pistons 26 and 23 increases in the application and piston 26 slows down in movement to a stationary position-against the spring pressure 27 and the built up fluid pressure. In normal operation piston 26 does not cover the passageway 40. Thereafter, in application of further force on rod 23h and piston i3, a higher pressure is placed on the system by the piston 23.

The vents 34, 38 and 39 provide for easy return of thev pistons 23 and 26 to their retracted positions where normal pressures in the system are restored.

vShould check valve 41 mal-function piston 26 moved by rod 23b and resilient connection 28v would move further to the left closing passageway 40 and there would be a closed system 18, 29 17 and 11 ahead of piston 26 which would then perform its intended function with but a small additional travel over that required for normal operation. Upon retraction of; rod 23,12, piston 23C will uncover passageway 34 thereby venting return system fluid into cylinder 18 and permitting-spring 27 to return piston 26 to its normal retracted position, uncovering passageways 40 and 39 whereby normal operation is restored.

- Additionally, should there be a leak in the system at the locus of cylinder 18 and piston 26 therein, piston 23 would still be effective as it would pass the portion of passageway 29e and there would be a closed system 11 and 17 thereahead of the piston 23 to apply pressure independent of the low pressure phase of the system. This is la fail-safe feature that is highly desirable especially in a vehicle braking system on which this apparatus is very adaptable for usage.

As can be seen, even should all check valves 41, 32 and 31 fail, the system will still operate to perform its intended function with but a relatively slight additional movement of piston rod 23'b over that required for normal operation. Thus, the system is a completely fail-safe system.

This actuating mechanism for a fluid-actuated system is relatively simple in construction and economical to manufacture, yet provides a highly reliable mechanism for applying fluid pressures in stages and for a high pressure fail-safe system independent of the lower pressure slack take-up incorporated system.

I claim as my invent-ion:

l'. An actuating mechanism for fluid-actuated brakes including, a first cylinder having fluid therein and having connection with said brakes, a second and larger cylinder lying adjacent and in line with said first cylinder, a first piston received in said first cylinder and extending through said second cylinder, a second piston mounted in said second cylinder and apertured to receive said first piston so as to extend therethrough, resilient means for connecting the pistons, a first conduit means connecting said second cylinder and the first cylinder at a position spaced ahead of said first piston in its retracted position, a vent conduit passage forming a communication between said second cylinderand said first cylinder at a position intermediate the connection of said first conduit means with the first cylinder and the first piston in its retracted position, check valve means in said first conduit means to prevent fluid flow from said first cylinder to said second cylinder, said resilient means causing both pistons to move as a unit until the second and larger pistons movement is interrupted, thereby first displacing a large amount of the fluid from the second cylinder under a relatively low pressure and then displacing a comparatively small amount of fluid under a high pressure as the first piston moves in the first cylinder, when power is applied to the first piston, said first conduit means being positioned next adjacent said vent conduit passage in its connection with said first cylinder adjacent the pressure applying face of said first piston whereby should the first piston move past said first conduit means connection with said first cylinder, a closed system containing actuating fluid is formed in said first cylinder ahead of said first piston.

2. An actuating mechanism for fluid-actuated brakes according to claim l wherein a biasing means is positioned between the pressure applying face of the second piston and the second cylinder for urging said second piston to a retracted position.

, 3. An actuating mechanism for fluid-actuated brakes according to claim 1 including a fluid reservoir, vent con-4 duitsconnecting said reservoir to said second cylinder at positions to either side of said second piston in its retracted position and a second conduit means-connecting said reservoir and said second cylinder at a point further removed from the pressure applying face of the second piston than the vent conduit thereadjacent, said said second cylinder to said reservoir.

4.` An actuatingmechanism for fluid-actuated brakes according to claim 4 wherein said second passageway connecting said resevoir and said second cylinderway is positioned next adjacent said vent passageway adjacent the pressure applying face of said second piston whereby should the second piston move past said second passageway a closed system containing actuating fluid is formed in said second'cylinderway ahead of said second piston.

5. An lactuating mechanism for fluid-actuated bralkes, comprising in combination, a main body, said main body having a first cylinderway -therein for fluid and connectable with said brakes, a second and larger cylinderway having an inner end lying adjacent and in line with said first cylinderway and receiving fluid therein and a reser- Voir for fluid above said cylinderways, an apertured closure plug received in the other end of said second cylinderway, a first piston received in said first cylinderway and extending through said second cylinderway and the aperture-in said apertured plug and adapted to have power applied thereto, a second piston mounted in said second cylinderway and apertured to receive said first piston so as to extend therethrough, resilient means for connecting the pistons and holding Said first piston retracted in the absence of power applied to the first piston, a first` passageway in the body connecting said second cylinderway and the first cylinderway at a position spaced ahead of said rst piston in its retracted position, a vent passageway in said body forming a direct communication between said second cylinderway and said first cylinderway at a position intermediate the connection of said first passageway with the first cylinder and the first cylinder' way and the end of the first piston in its retracted position, check valve means in said first passageway to prevent fluid flow from said first cylinderway to said second cylinderway, said resilient means causing both pistons to move as a unit until the second and larger pistons movement is interrupted, vent passageways in the main body connecting said reservoir with said second cylinderway at positions to either side of said second piston in itsk retracted position and a second passageway in said body connecting said reservoir and said second cylinderway at a point further removed from the pressure applying face of the secured piston than the vent passageway thereadjacent, said second passageway connecting the reservoir and second cylinderway having a check valve therein preventing 'fluid flow from said second cylinderway to said reservoir sai-d second passageway connecting said reservoir and said second cylinderway being positioned next adjacent said vent passageway adjacent'the pressure applying face of said second piston whereby should the second piston move past said second passageway a closed system containing actuating fluid is formed in said second cylinderway ahead of said second piston.

6. An actuating mechanism for fluid-actuated brakes according to claim 5 including a-biasing means positioned between the pressure applying face of the second piston and the second cylinder for urging said second piston to a retracted position.

7, An actuating mechanism for a fluid-actuated mechanism including, a first cylinder having fluid therein and having connection with said fluid-actuated mechanism, a second and larger cylinder lying adjacent and in line with said first cylinder, a first piston received in said first cylinder and extending through said second cylinder and adapted to have power applied thereto, a second piston mounted in said second cylinder and apertured to receive said -first piston so yas to extend therethrough, resilient means for connecting the pistons and holding saidfirst piston retracted in the absence of power applied to the first piston, biasing means between said second piston and cylinder for urging said second piston to a retracted position, a rst conduit means connecting said second cylinder and the iirst cylinder `at a position spaced ahead of said first piston in its retracted position, a ventV conduit passage forming a communication between said second cylinder and said first cylinder ata position intermediate the connection of said first conduit means with the iirst cylinder and the first piston in its retracted position, check valve means in said first conduit means to prevent fluid fiow from said first cylinder to said second cylinder, said first resilient means causing both pistons to move as a unit until the second and larger pistons movement is interrupted, said first conduit means being positioned next adjacent said vent conduit passage in its connection with said first cylinder adjacent the pressure applying face of said first piston whereby should the first piston move past said first conduit means connection with said first cylinder, a closed system containing actuating fluid is formed in said first cylinder ahead of said first piston.

8. An actuating mechanism for a fluid-actuated mechanism according to claim 7 including a fluid reservoir, vent conduits connecting said reservoir to said second cylinder at positions to either side of said second piston in its retracted position and ya second conduit means connecting said reservoir and said second cylinder at a point further removed from the pressure applying face of the second piston than the vent conduit means connecting the reservoir and second cylinder, said second conduit means having a check valve therein preventing fiuid ow from second cylinder to said reservoir.

9. An actuating mechanism for a duid-actuated mechanism according to claim 8 wherein said second conduit means connecting said reservoir and second cylinder is positioned next adjacent said vent conduit means adjacent the pressure applying face of said second piston whereby should the second piston move past said second conduit. means in its connection with said second cylinder, a closed system containing actuating fluid is formed in said second cylinder ahead of said second piston.

10. An actuating mechanism for a duid-actuated mechanism comprising in combination, `a main body having a first cylinderway therein for fiuid and connectable with said fluid-actuated mechanism, a second and larger cylinderway having an inner end lying adjacent Iand in line with said first cylinderway and receiving fluid therein and a reservoir for fluid above said cylinderways, an apertured closure plug received in the other end of said second cylinderway, a first piston received in said iirst cylinderway and extending through said second cylinderway and the aperture in said apertured plug and adapted to have force applied thereto, a second piston mounted in said second cylinderway and apertured to receive said first piston so as to extend therethrough, resilient means for connecting the pistons and holding said rst piston retracted in absence of` force applied tov the first piston,

biasing means between said second piston and cylinder forurging said second cylinder to a retracted position, a first passageway in the body connecting said sccondcylinderway and the rst cylinderway at a position spaced ahead of said firstl piston in its retracted position, a vent passageway in said body forming a communication between said second cylinderway and said iirst cylinderway at a position intermediate the connection of said first passageway With the first cylinderway and the end of the first piston in its retracted position, check valve means in said'first passageway to prevent uid ow from said first cylinderway to said second cylinderway, saidl resilient means causing both pistons to move as a unit until the second and larger pistons movement is interrupted, vent passageways in the main body connecting said reservoir with said second cylinderway at positions to either side of its retracted position and a second passageway in said body connecting said reservoir and said second cylinderway at a point further removed from the pressure applying face of the second piston than the vent passageway thereadjacent, said second passageway connecting the reservoir and seco-nd cylinderway having a check valve therein preventing fiuid ow from said second cylinderway to said reservoir.

11. An actuating mechanism for fluid-actuated mechanism according to claim 10 wherein said check valve means in said first passageway comprises a spring pressed ball check.

12. An actuating mechanism for duid-actuated mechanism according to claim 10 wherein said check valve means in said first passageway comprises a spring pressed reciprocable valve element seating against a non-metallic sealing seat.

13. An actuating mechanism for fluid-actuated mechanism according to claim 10 wherein said second passageway connecting said reservoir and said second cylinderway is positioned next adjacent said vent passageway adjacent the pressure applying face of said second piston whereby should the second piston move past said second passageway, a closed system containing actuating fluid is formed in said second cylinderway `ahead of said second piston.

14. An `actuating mechanism for fluid-actuated mechanism according to claim 10 wherein said first passageway is positioned next adjacent said vent passageway in its connection with said first cylinderway adjacent the pressure applying face of said first piston whereby should the iirst piston move past said first passageway connection with said first cylinderway, a closed system containing actuating fluid is formed in said first cylinderway ahead of said first piston.

Troy Mar. 27, 1956 Johnson et al. Aug. 27, 1957 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent Nm, `2,955Y427 October ll, 1960 Lloyd G. i Porkert It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6Y line 13I for the claim reference numeral "4" read 3 line 14g for Pesci/oir" read reservoir signed and sealed this 25th day of April 1961.,

(SEAL) Attest:

ERNEST w., SWIDER DAVID Lo LADD Attesting Officer Commissioner of Patents 

